package jisuan4h9t;

import java.util.Scanner;

public class qiuArea {
    final static double PI = 3.1415927;
    public static void main(String[] args) {
        Scanner reader = new Scanner(System.in);
        double r,v;
        while(reader.hasNext()) {
            r = reader.nextDouble();
            v = PI * r * r * r * 4 / 3.000;
            System.out.printf("%.3f", v);
            System.out.println();
        }
    }
}
